The commercial success of bar code reading equipment utilizing portable beam scanning equipment is well known. As the field continues to advance, users of portable data collection equipment demand ever smaller scan systems with more computerized features and greater convenience of operation. Productivity in the portable data collection industry is dependent on ease of operation of light weight equipment. Acceptance of such equipment by those who operate it on a daily basis depends upon the ergonomic features of scanning devices and terminals.
In some environments where users may be required to climb ladders to capture data, "hands free" and/or wearable scanning equipment is desirable and can lend to the safety of the operator if properly designed. Therefore, the way in which scanners are turned on and off is a significant ergonomic consideration in the design of portable scanning equipment.
The present market place continues to demand scanners which are smaller, lighter, lower cost, lower power with higher functionality, and now even wearable data collection systems are coming into demand.
As will be shown, the present invention advances the state of scanning art by providing fatigue reducing, novel actuation methods, low mass systems and wearability features which greatly reduce operator fatigue produced by mechanical switch mechanisms, heavy equipment, encumbering cables and the like.
Numerous hand holdable portable data collection systems for reading bar code have been successful in the market. These generally fall into two classes: (i) those which scan and read a bar code, then send the data to external data processing systems, (ii) and those in which scanners are integrated within data processing terminals.
Among the hand holdable portable scanners, gun-shaped scanners have been popular, such as the non-contact laser scanner described in U.S. Pat. No. 4,387,297. This scan system utilizes a mechanical trigger mechanism on the outside of the housing and is operated by squeezing the trigger with the index finger. This technique, however, can cause user fatigue. The trigger requires numerous parts to effect spring loaded lever action of an internal electromechanical switch. An opening in the housing is also necessary to allow for mechanical linkage of the external trigger to the switch inside the housing, thus rendering the housing difficult to seal against moisture or other contamination. Making such a scanner intrinsically safe in an explosive fume environment is also difficult due to the sealing problem.
U.S. Pat. No. 5,260,553 describes a hand holdable scanner with a non-scanning light source (i.e., a light source other than the beam scanning light source) which reflects off of a target (e.g., a bar code). The non-scanning light source works in conjunction with a separate special detector to ascertain target distance or presence. If the target is within scanning range, the scanner is then signaled to turn on. This scheme, although it does away with a certain amount of user fatigue, has been known to cause some user frustration because the target's ability to reflect the non-scanned light can influence the point at which the unit goes on rather than its true distance from a target. Also, considerable light must be continuously emitted to "see" distant targets, hence, precious battery power is consumed.
U.S. Pat. No. 4,639,606 discloses laser emission control circuitry for use in implementing hand-held bar code equipment operation. The laser is operated in a pulsed "find paper" mode until a reflected signal is obtained indicating the presence of a target in the search field, where upon scanning is automatically initiated. Since this system requires continuous use of a pulsed-laser beam to determine the presence of an object within the scan field, it consumes significant power to energize the laser. (Most commonly available solid state laser diodes require tens of milliamps and voltages in excess of 2 volts to operate.) Also, the control circuitry for solid state laser control is not simple, especially when several discrete power modes, including pulsed modes, are desired. This increases system bulk and cost.
Scanners with integrated terminals suffer from the same drawbacks as do the systems mentioned above. One prior art scan system such as the one illustrated in FIG. 7 is a wearable scan system. It works with an arm mounted terminal and has a cable attached between the scanner and the terminal. The scanner portion has a mechanical thumb operated switch lever similar to the trigger described in U.S. Pat. No. 4,387,297. The lever is clumsy, leads to operator fatigue and suffers from all the difficulties of gun style scanners. Removal of this finger mounted system is also inconvenient because of the cable. The finger mountable scan head is quite bulky and can lead to user discomfort due to the size and mass of the unit which carries all the internal parts of a complete scanner including light detection circuits.
In general, the portable prior art scan systems cited above suffer from size, power usage, and ergonomic difficulties.